Gaseous conduction apparatus



March 20, 1934.

c. G. SMITH 1,951,808

GASEOUS CONDUCTION APPARATUS Filed Dec. 5, 1928 Patented Mar. 20, 1934 GASEOUS CONDUCTION APPARATUS Charles G. Smith, Medford, Mass, assignor, by mesne assignments, to Raytheon Manufacturing Company, Newton, Mass, a corporation of Delaware Application December 5, 1928, Serial No. 323,901

9 Claims. (Cl. 176-122) It is highly desirable in certain fields, notably television and photographic recording of sound,

that means for rapidly and accurately varying the intensity of light in accordance with varia- 6 tions of electrical currents be present. My invention relates to a gaseous conduction apparatus which is adapted to be used for such purposes. Ordinary glow-lamps in which spaced electrodes operate in the presence of a gas are capable of l fulfilling the functions of a rapidly varying light in accordance with rapidly varying currents but suifer from certain defects. These defects. are the blackening of the container by electrode sputtering and also a comparatively high amplitude of modulation for varying the intensity of the light.

A further defect is the fact that the light from such lamps is diffused and of low luminous in tensity.

An object of my invention is to devise a lamp which will not become blackened by electrode sputtering. A further object is to devise such a lamp so that the modulating waves need not have very great amplitude in order to cause the lamp to operate.

A further object is to devise a glow-lamp which will have a concentrated intense glow whereby such devices as photo-electric cells, photographic film, and other light sensitive substances will be more powerfully affected.

In general, one specific embodiment of my invention comprises a hollow cathode enclosed by electrode act to shift the seat of discharge from the anode to the other or grid electrode, thereby rendering the discharge visible. 1 the modulated currents has its counterpart in the intensity of the discharge.

In another embodiment of the invention, I have substantially the same structure except that the hollow enclosing anode is entirely omitted. The discharge is at all times between the hollow cathode and the ring anode.

Referring to the drawing, Figure l is a sectional view of my improved lamp.

The intensity of Figure 2 is a diagrammatic arrangement or a system employing my improved lamp.

The lamp in Figure 1 comprises a container 1 of glass or any other suitable material having a reentrant pcrtion 2 terminating in a press 3. Q0 Press 3 has a tubular member 4 upon which is supported an insulating member 5 of lava or similar material. Suitably suppQrted by lava 5 is a cathode 6 having a hollow cup shape. The bottom thereof may be suitably shaped so that 55 it intorfits with the insulating member 5 so as to be firmly maintained thereby. This cathode may be of any material such as nickel or carbon with a coating of alkali metal or alkaline earth metal oxides. A lead wire '7 suitably sealed in 10 ,press 3 goes through insulator 5 and connects with cathode 6 maintaining said cathode firmly against insulating member 5. Around cathode 6 is a hollow anode 8. This anode is composed of an annular member 9 supported by wires 10 7 and 11 suitably sealed in press 3. Wire 10 goes through the press and acts as a lead for the anode. Cylindrical portion 12 of the anode is welded or otherwise secured to annular member 9 so as to be maintained thereby. The other end of the anode is composed of a member 13 which may be integral with cylindrical member 12 if desired. This member 12 comprises an annular region and a depending flange member 14. Flange member-l4 of the anode is smaller than the opening of 'the cathode and is below the edge thereof. Above the anode and substantially concentric with the cathode and anode is a ring shaped grid electrode 15 suitably supported by a wire member 16 sealed in press 3 and which also serves as a leadin therefor.

The tube is exhausted and deprived of occluded gases in accordance with .the usual practice and then filled with a rare gas to a pressure of around 6 m. m. Preferably I employ neon on account of its high luminous qualities when passing current.

In order to use the tube, connect cathode 6 to the negative pole of a source of current at a suitablepotential. Prefera'oiy I insert a resistance R in the circuit to stabilize the discharge and prevent the negative characteristics of the discharge from interfering with the proper functioning of the system. To the positive pole of the source of current is connected 2. lead '20 to a condenser C, the other pole of which is connected by lead 10 to the anode of the tube. Bridged across from lead 10 to an intermediate portion of the battery is an inductance L., The intermediate portion of the source of potential 110 is so chosen that the potential through circuit 7, cathode 6, anode 8, lead 10, inductance l1, and source of current is sufficient to maintain a steady discharge between the cathode and anode. Lead 16 of grid 15 is connected through a transformer T to lead 20. Transformer T is connected to a suitable system whereby modulated currents are conducted to it. Grid 15 will have a positive bias with relation to anode 8. Condenser C serves to prevent the biasing portions of the source of potential from short circuiting through inductance L. A lens G is shown as -being focused in such manner that any visible discharge from the tube will be properly collected into a parallel beam.

In operation the potential difference between cathode 6 and anode 8 is sufficient to maintain a dull steady discharge. Inductance L prevents any fluctuation in the discharge. As soon as a modulated impulse arrives at transformer T, the additional potential above 'the biasing potential will sufiice to cause the discharge between the cathode and anode to be shifted to between the cathode and grid. The greater the amplitude of the modulated impulse, the more intense the discharge between the cathode and grid 15. By suitably adjusting the bias with respect to the anode, it is possible to cause the discharge between the cathode and anode to change'to between the cathode and grid with a very slight impulse. The discharge between'the cathode and grid will take place between the inside surface of the cathode and grid. The discharge will be concentrated into a comparatively small space and not be spread over a very large area, as customary; By suitably adjusting lens G or a system of lenses, it is possible to make full use of the varying light impulses.

Any tendency of the cathode to sputter will merely transfer the sputtered particles to the inside surface of the anode and have no effect on the operation of the tube.

Instead of causing a glow-like discharge by direct current, it is possible to have a high frequency alternating current pass between the two electrodes and cause a discharge. By having an extremely high frequency, such as 10,000 cycles per second, the brilliancy of the glow discharge may be greatly increased. The reason for the inof ions and electrons as well as the assumption of the natural state by excited particles takes place. This happens with the evolution of light. This phenomenon takes place with great speed, and therefore, if high frequency currents are employed there is little to lose between the complete disappearance of ionized particles and the formation of newly ionized and excited particles. Hence, while with high frequency there may be the same amount of light per cycle as with low frequency, the greater numberof cycles per second, results in a light which is more brilliant.

This brilliancy may be modulated by radio frequency or television impulses in the same manner as carrier waves are modulated.. The tube shown in Figure 1; may thus'be operated also.

The battery would be replaced by a source of high frequency alternating current. By suitably regulating the two potentials, it would be possible to have the discharge shifted to the grid electrode with the aid of modulating potentials.

Thus it is evident that I have disclosed a tube in which a glow-like discharge gives rise to a brilliant and highly actinic source of light which may be easily and rapidly modulated for any purpose desired.

I claim:

1. A gaseous conduction device comprising the combination with an exhausted envelope, containing an attenuated atmosphere of a hollow anode, a'hollow cathode enclosed by the said anode, the said cathode having an open end, a flange on the said anode entering the open end of the cathode, the said flange having an aperture communicating with the inside of the cathode, and a third electrode positioned adjacent the said aperture, the .said electrode being adapted to be maintained at a higher potential than the anode, and also being adapted to receive modulated impulses, whereby a discharge between the anode and cathode is shifted to the said third electrode.

2. A gaseous conduction device comprising a cathode having an appreciable area, an anode, means for producing a dull glow discharge between said anode and a relatively large portion of said cathode, a third electrode, and means for shifting said glow discharge between said third electrode and a relatively small area on said cathode, whereby said glow discharge becomes more brilliant.

3. -A gaseous conduction device comprising a cathode having a cavity therein, an anode, and athird electrode, said anode being arranged adjacent the external surfaces of said cathode, whereby a glow discharge may be maintained between said anode and said external surfaces of said cathode, and said third electrode being arranged adjacent the cavity in said cathode, whereby the path of the discharge may be shifted to between said third electrode and the cavity in said cathode.

4. A gaseous conduction device comprising a cathode having a cavity therein, a hollow anode surrounding said cathode, a restricted opening in said anode adjacent said cathode, a third electrode positioned outside of said anode adjacent said opening, means for maintaining a glow discharge between said anode and the exterior of said cathode, and means for shifting the path of said discharge to between said third electrode and the cavity in said cathode.

5. A gaseous conduction device comprising a cathode having a cavity therein, a hollow. anode surrounding said cathode, and a third electrode presented to said cathode opposite the cavity therein, said anode cutting ofi all discharge paths between said third electrode and said cathode, exceptbetween said third electrode and the cavity within said cathode.

6. A gaseous discharge lamp comprising a transparent gas-filled sealed envelope, a cathode,

and an anode within said envelope, said anode and cathode being adapted to support a discharge between said anode and a portion of said cathode, said anode being opaque, opaque means including said anode interposed between said discharge and said envelope and intercepting all straight-line paths between said discharge and said envelope, and a third electrode, said opaque means being provided with a direct discharge path between said cathode and said thirdelectrode, said cathode and third electrode being adapted to support an intense discharge through said latter discharge path.

7. A gaseous conduction device comprising a cathode having a cavity therein, a hollow anode, and a third electrode, said anode surrounding said cathode and adapted to maintaina diffused, dull glow discharge between said cathode and said anode, an opening in said anode adjacent said cathode, said third electrode being arranged adjacent said cathode to support a discharge to said cavity in said cathode, whereby the path of the discharge may be shifted to between said third electrode and the cavity in said cathode.

8. A gaseous conduction device comprising a cathode having a cavity therein, a hollow anode surrounding said cathode, and a third electrode arranged adjacent said cathode to support a discharge to said cavity, said anode cutting off all discharge paths between said third electrode and said cathode, except between said third electrode and the cavity within said cathode.

9, A gaseous conduction device comprising a cathode having a cavity therein, a hollow anode surrounding 'said cathode, an opening in said cathode adjacent said cathode cavity, a third electrode positioned outside of said anode adjacent said opening, means for maintaining a glow discharge between said anode and the exterior oi said cathode, and means for shifting the path of said discharge to between said third electrode and the cavity in said cathode.

CHARLES G. SMITH. 

